Method and device for collecting oil mixed with ice blocks

ABSTRACT

A method and a device for separating oil from ice. In the method, ice is pressed under the water along an inclined surface formed by a bar screen ( 3 ) or a grating. The oil is separated from the ice by vibrating the inclined surface formed by the bar screen ( 3 ).

BACKGROUND OF THE INVENTION

The objective of the invention is a method and a device for collectingoil mixed with ice blocks.

As a consequence of ships striking a rock, colliding or equipmentfailure, oil can get into the water. Collecting oil from water isespecially difficult when the water is partly or fully covered by ice.The situation is particularly difficult when the oil is in a broken icefield, such as a fairway. In that case, oil is not only on the lowersurface of the ice, but also mixed with the ice blocks and trash iceand, to some extent, even on top of the ice. Collecting oil from iceblocks by using the equipment on the market has not been efficientenough. The state of the art recognizes a low-gradient plane that pushesice blocks under the surface of the water; as a result, part of the oilcomes off, and the dispersed oil can be recovered by using variousmethods.

Patent publication FI 80746 describes an application on board a vesselto collect oil from among ice blocks. The application comprises a bowmember with a low gradient, planar lower surface that is provided withintake openings for water containing impurities. When the vessel movesforward, ice blocks are submerged below the surface and are washed atthe same time. According to the publication, intensive waterjets canenhance washing. The bow is a part that is separate from the actual bodyof the vessel and it can be lifted and lowered to achieve optimaldriving conditions.

Patent application FI 73029 describes a method for collecting oil from awater level covered with ice. In the method, if needed, ice is brokeninto small enough pieces so that they can be submerged below the waterlevel by using the equipment available. Oil, that comes off the iceblocks by washing with water streams that are generated by submergingthe ice blocks, is recovered.

Patent application U.S. Pat. No. 4,039,454 describes a device forseparating oil from water and floating ice blocks. This device alsocomprises an inclined plane that forces the ice blocks under water. Theplane consists of a grating through which the oil can rise and betransferred to the collection equipment. Oil is removed from ice blockswhen the ice blocks are submerged under the water.

Patent publication FI 75014 describes an application on board a vesselfor collecting oil from among ice blocks. The lower surface of thevessel bow is low-gradient so that, when the vessel moves forward, iceblocks are submerged under the water, simultaneously being washed by thewater. The lower surface of the inclined plane comprises bristles thatsweep the upper surfaces of the ice blocks. The lower surface of theplane comprises water intake openings and the oil is separated from thewater inside the vessel. The water that is pumped out is sprayed on theice blocks from which the oil is to be removed.

In prior art solutions, the separation of oil from the ice blocks issolely based on the buoyant force of oil in relation to water, when iceblocks are forced under the water level. This separation method is notefficient and the majority of the oil remains attached to the iceblocks. By using the method and the equipment according to theinvention, oil can be removed from ice blocks considerably moreefficiently than before.

SUMMARY OF THE INVENTION

The objective of the invention is a method for separating oil from iceblocks, comprising forcing the ice blocks under the water along aninclined surface formed by a bar screen or a grating attached to thevessel. The method is characterized in that oil is separated from iceblocks by vibrating the inclined surface formed by the bar screen.Vibrating is preferably effected in an essentially vertical direction.The pounding movement of the bar screen now drives the ice downward andthe buoyant force of the water returns them to the bar screen. As aresult of the impacts, oil is detached from the ice and it rises to thewater level above the bar screen, from where it can be collected byusing various methods.

Another objective of the invention is a device for the method describedabove. The device, comprising an inclined surface formed by a bar screenor a grating for forcing ice blocks under water, is attached to the sideor bow of the ship and, when the ship is propelled, a movement thatforces the ice downwards is generated. The device is characterized inthat oil is separated from the ice blocks by vibrating the inclinedsurface formed by the bar screen. Vibrating is preferably effected inessentially the vertical direction.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is described with reference to theappended drawings in which:

FIG. 1 shows the operating principle of the device according to theinvention to separate oil from ice,

FIG. 2 is a side view of a device according to the invention, and

FIG. 3 shows a view of a bar screen according to the invention as viewedfrom below.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Device 2 according to the invention is either detachably or fixedlyattached to the side or the bow of a vessel. Device 2 is preferablyattached so that it can be detached, so that the vessel can also be usedfor other purposes. Furthermore, a preferred location is on the side ofthe ship, as the screw can see device 2, which improves security and noseparate personnel are needed for the operation of device 2.

When the vessel moves forward, ice blocks 1, among which and attached towhich there is oil, are forced under water along the inclined planeformed by bar screen 3 or a grating. Bar screen 3 is preferably inclinedin such a way that, as a result of the ship's movement, the ice blocksslide along the inclined plane and the plane does not push them in frontof it. A preferred inclination is, e.g., about 13 to 15 degrees. Barscreen 3 is preferably made of steel or other material that is suitablefor the purpose.

Bar screen 3 is vibrated by a method known per se, for example, byeccentric mass or a crank mechanism. Bar screen 3 is moved in thevertical direction, pivoted axle 7 limiting the movement of its otherend. The pivoted axle can be located on the leading or the trailing edgeof device 2. Device 2 can also be moved back and forth by using linearguides, or vibration can have a rotating trajectory. Vibration ispreferably effected essentially in the vertical direction but can alsobe carried out obliquely forward or backward.

In one embodiment according to the invention, illustrated by FIG. 2,pivoted axle 7 is located as far front as possible, so that there is asubstantial amount of movement for bar screen 3 on the water level. Areciprocal movement is effected by push-pull rod 8 attached to the rearend of device 2, the rod being propelled by eccentric mass 6 rotated bya suitable, power-generating device, such as electric or hydraulic motor9. The rotative velocity and the stroke of eccentric mass 6 can beadjusted. By adjusting the length of stroke, the amplitude of vibrationcan be changed and by adjusting the rotative velocity, the frequency ofvibration can be changed.

The pounding movement of bar screen 3 drives ice blocks 1 downward andthe buoyant force of the water puts them back in contact with the barscreen. As a consequence of the impacts, oil is detached from ice blocks1 and rises to the surface of the water to collecting space 4 above barscreen 3, from where it can be transferred by using water flow 5, forexample, to an oil separation unit that is preferably located inside theship, so that it is not exposed to the stress caused by ice or coldness.On the market, there are various methods that are suitable forseparation.

Bar screen 3 allows the water to freely drift above it, but holds themajority of ice blocks under it. Other grate-type plates can also beused, provided that they do not prevent the water from drifting.

Adjusting the direction of vibration so that it feeds ice under barscreen 3 can enhance the drifting of ice blocks 1 under bar screen 3.Furthermore, the drifting of ice blocks 1 under bar screen 3 can beenhanced, for example, by locating a paddle wheel or other activeice-feeding device in the front end of device 2.

Bar screen 3 can also be located in device 2 so that the part formed bybar screen 3 is horizontal so that the pitch angle is replaced by anS-upslope at the bow.

The method and the device according to the invention are especiallyviable on a fairway where there is passage broken for traffic or apassage caused by ship traffic. The device can also be attached to anicebreaker, so that the same vessel can first break the fast ice andafter this or at the same time carry out oil separation from the ice byusing the method according to the invention.

The description discloses some embodiments of the invention. However,the invention is not limited to only relate to these special cases butthe various features of the invention can be modified within the extentof the appended claims without leaving the scope of the invention.

What is claimed is:
 1. A method for separating oil from a mixture of iceblocks and water, comprising forcing the ice blocks (1) under the wateralong an inclined surface at least partly formed by a bar screen or agrating (3) attached to a vessel, while the vessel moves forward,wherein the oil is separated from the ice blocks (1) by vibrating, backand forth against the ice blocks (1), the inclined surface comprisingthe bar screen or the grating (3).
 2. A method according to claim 1,wherein vibration is effected essentially in the vertical direction. 3.A method according to claim 1, wherein vibration is effected obliquelyforward or obliquely backward.
 4. A method according to claim 1, whereinvibration is caused by an eccentric mass (6) or a crank mechanism.
 5. Amethod according to claim 1, wherein the oil that has come loose as aconsequence of vibration is collected through a collecting space (4) toan oil separation unit, wherein the water and the oil are separated. 6.A device attached to a vessel for separating oil from a mixture of iceblocks and water, the device (2) comprising an inclined surface at leastpartly formed by a bar screen or a grating (3) for forcing the iceblocks (1) under the water while the vessel moves forward, wherein thedevice comprises a means for vibrating the inclined surface comprisingthe bar screen or the grating (3) back and forth against the ice blocks(1) for separating the oil from the ice blocks (1).
 7. A deviceaccording to claim 6, wherein the device (2) is attached to the side orthe bow of the vessel.
 8. A device according to claim 6, wherein thedevice (2) is attached to the vessel so that it can be detached.
 9. Adevice according to claim 6, wherein the device (2) is fixedly attachedto the vessel.
 10. A device according to claim 6, wherein the vessel isan icebreaker.